View Full Version : Power supply & Grinch question

02-11-2008, 08:46 PM
Okay I finally got everything working, Grinch with a Ren-t and Ren-c. Using a usb to serial adapter. The problem I had (still have) is I have an external power supply from a old lan hub, it has 5v and 12v outputs. The 5v is 5.13v and the Allegro or the MBI chips wouldn't work. Someone suggested putting a diode 1N4001 on the power supply which I did and it brought the 5v supply down to 4.37v again the Allegro chips wouldn't work but the MBI chips did. So at what voltage will the Allegro chips work and how do I get the power to that voltage? I tried the power from my desktop and it matches the external power supply almost excatly. Should I just buy an adjustable 5v power supply to try and get the Allegro chips to work or just stick with the MBI chips? I'm conserend that once I hook up a second ren-c and grinch that the 4.37v will drop further and everything stop working. I just don't want to wait until christmas and find out I can't get everything to work properly.


After doing some reading I found a simular power supply to the one I have so I opened the case and was able to adjust the power down. I set it down to 4.8v and everything seems to work, including the Allegro chips.
Thanks everyone, I guess that this summer I'll set up in the garage and try alot of lights to make sure everything is ready so not doing it in the cold and last minute.

P. Short
02-11-2008, 09:14 PM
If you are using Ren-C for the Grinch (instead of connecting the Grinch directly to the parallel port), it should run on that power supply (without any need to lower the voltage). I don't know why you are having problems, but make sure all of the grounds are connected together...



02-11-2008, 10:03 PM
How long are your cables between the Ren-C and the Grinch?

Most people who have had problems seem to fix them by keeping the cables less than 6" in length.

BTW: The Allegro chips operate on a lower HIGH voltage than the MBI chips so I don't think that you are having a voltage issue.

01-18-2009, 10:47 PM
Just wondering if a 1N4004 was ok to use instead of the 1N4001 to drop v to a grinch.